Production and characterization of gypsum-based composites reinforced with cocoa agroindustry waste particles

ABSTRACT This work aimed to produce and characterize gypsum-based composites reinforced with cocoa waste particles as a way to add value to this agricultural by-product and create an innovative material. For the production of composites, thin plaster for casting and particles of cocoa waste were used. The reinforcement proportions inserted were 0.0%; 2.5%; 5.0%; 7.5% and 10.0% replacing plaster mass. For the production of composites, wooden molds with dimensions of 40 x 40 x 160 mm were used. Analysis of the chemical composition of the cocoa waste was performed to determine the levels of total extracts, ash, lignin and holocellulose. The composites were evaluated in physical, mechanical, thermal and acoustic tests. It was found that there were improvements in physical properties with the addition of reinforcement making the material lighter, given the reduction in density (1190.69 to 1138.92 kg/m³), ??and providing a decrease in hygroscopicity, with moisture levels decreasing from 7.74 to 4.01% and water absorption decreasing from 18.37 to 5.28%. Likewise, the thermal resistance gradually increased over the treatments with values ??from 1.90 to 2.41 K.m/W and the acoustic insulation was higher in composites compared to pure plaster, although there was no linearity between treatments. As for the mechanical properties, there was a decrease in resistance both to flexion (3.60 to 0.84 MPa) and to compression (4.43 to 1.73 MPa). It was concluded that the cocoa waste has the potential to be used in the composite considering that the inclusion of up to 8.15% of the same met the standard in all tests performed. This promotes the idea that lignocellulosic waste is a promising alternative for creating materials with high added value.

摘要 本研究旨在制备并表征以可可废料颗粒增强的石膏基复合材料，以期提升该农业副产物的附加值并开发新型建材。本研究采用浇注用建筑石膏与可可废料颗粒制备复合材料，增强相添加比例分别为0.0%、2.5%、5.0%、7.5%及10.0%（以石膏质量计）。复合材料制备过程中，采用尺寸为40×40×160 mm的木质模具。对可可废料开展化学成分分析，以测定其总提取物、灰分、木质素及综纤维素含量。对制备的复合材料进行物理、力学、热学及声学性能测试。研究结果表明，添加增强相可改善复合材料物理性能：材料密度从1190.69 kg/m³降至1138.92 kg/m³，质量更轻；同时吸湿性降低，含水率由7.74%降至4.01%，吸水率由18.37%降至5.28%。同样，随着增强相添加比例提升，复合材料热阻逐步升高，从1.90 K·m/W增至2.41 K·m/W；相较于纯石膏，复合材料隔声性能更优，但各添加比例间未呈现线性变化规律。力学性能方面，复合材料抗弯强度（从3.60 MPa降至0.84 MPa）与抗压强度（从4.43 MPa降至1.73 MPa）均出现下降。综上，当可可废料添加比例不超过8.15%时，复合材料可满足所有测试的标准要求，因此可可废料具备用于制备复合材料的潜力。该研究证实，木质纤维素类废料是开发高附加值新型建材的极具前景的替代原料。